Transmitter



June 17, 1930. H. F. FRUTH E AL I TRANSMITTER Filed'Oci. 11. 1927 fZ/f/iEwe/me dWas/Mfer m 4/2 7 p Il Navy-,1 i

minal metallic clamping ring. The assembl f these parts presentsatransmitter button avao-considered in connection with.

' numerals a button which includes lation, and

disclosed 'in Figs. 2 an Patented June 1 rest ramsarrrrnn I Applicationfiled. October 11, 1927. Serial No.

This invention relates to transmitters, and

'more particularly to resistance varying apparatus for telephonetransmitters.

e primary object of this invention is to provide a simple,- andefficiently "operable resistance varying means for electricaltransmitters.

In accordance with the general features of the invention one embodimentthereof comprises a telephone transmitter provided with a back electrodeas sembly comprising a carbon disk clamped between an insulating cup anda metallictermember. Granular carbon is positioned within the cupadjacent the front electrede assembly which includes a'carbon disksecured by an alloy of low melting point within a metallic cup. Abi-metallic, corrugated diaphragm comprised of metals having differentcoeficients of expansion centrally supports the front electrode assemblyand is clamped between the insulating cup and a mg a mlnimum number ofelements assem bled in a very convenient and economical manner, a .Theseand other-objects will be apparent from" the following detaileddescription when the accompanying drawings, wherein ig. 1 is a sideelevational view disclosing an application of the invention to acommercial type of telephone transmitter, a portion thereof being shownin section to more clearly indicate structures otherwise hidden J .Fig.2 isa-central, longitudinahsectlonal F1 1; I v

' ig. 3 is-a view showing parts of the trans- Initter button in sectionand in separated re- Fig. 4 is-an enlarged fragmentary detailedsectional view of the ,gi-metallic diaphragm Referringnow to the drawingwherein like economically constructed have been employed to designate.similar parts throughout thevarious'figures',

' it will be observed that-Fig. 1 dlscloses a teleprovided with theusual numeral 10 which is mouthpiece l1 threaded within a face plateSecured to the rear of this face plate 12 isa metal bridge piece 14which is provided medially thereof with a mounting .member 15. A setscrew 16 serves to secure a metallic shank 18 of a transmitter buttongenerall by the numeral tion wit 1in the mounting member 15.

his transmitter button 19 comprises an internally threaded metal flangeor terminal section 20 formed integral indicated 19 in a fixed posiwiththe shank 18 which forms a part of the back assembly I of the button 19.This back assembly also includes a carbon disk 22 clamped against thefront' surface of the flange 20 by means of an insulating cup 23 andforming an elecring 24 which serves to clamp a bi-metallic. annulus ordiaphragm 26 against the front surface of the cup.

This bi-metallic diaphragm 26 is provided with a pluralityof land iscentrally apertured to support the frontelectrode assembly of the button19 which includes a ber 28 clamped to of a clamping ring 30 and a carbondisk 31 ositioned with'n the r ce 'sed or on -sh ed View of thetransnntter button disclosed in p 1 S p ap ing point alloy 33, such astin, solder or other a1, and while'the alloy 33 is suitable materi stillmoltenthe disk 31 is pressed into position and the alloy permitted tomake a shrinking fit around the disk. By shrinking the carbon disk orelectrode .31 within the memer 28 which has been previously coated orelectrode 22 as the annular corrugations 27 metallic cup-shaped memthediaphragm 26 by meanstinned, a firm mounting of the disk 31 is veryconveniently efiected. p

. A supply of granular carbon 34 placed between the carbon electrodes 22and 31 serves to produce resistance variations in response to vibrationsofthe front electrode assembly. By having this diaphragm 26 ofbi-metallic construction, sheets. of metals having difierentcoeflicients of expansion, such as brass and another metal having a lowcoefficient of expansion, such as a nickel-steel alloy commonly known asinvar, a compensating efiectais produced which reduces to a minimumdeleterious results, such as undesirable'resistance variations, which'-in some instances may result from temperature variatransmitter is subected.

tions to which the of the granular carbon 34, parts associatedtherewith, begins to rise as soon as the telephone circuit is closed,and this rise'in temperature increases the contact resistance of thegranular carbon, sulting in a decrease in the current to less than itsoptimum; value. To compensate ior this derease, the diaphragm 26 may becon structed to move inwardly toward the carbon 34 upon increase intemperature, which grill increase the pressure within the carbon 4 andtend to decrease its resistance and increase the current. The diaphragmma also be so constructed as to compensate for t e expansion andcontraction of ring 24 and the other parts due to temperature changes,in which case the relative positions of the inetals constituting thediaphragm will be dependent upon the particular arrangement of th otherparts which constitute the transmitter button. The annular corrugations27 formed in the diaphra 26 lend s' fiicient rigidity thereto to enab ethe use of a relatively thin: metallic diaphragm, and thereby; introducea decided factor of economy in metallic diaphragm construction. i Thearrangement. f the described apparatus is advantageous in that itpresents a sistance. varying apparatus, the parts which are relativelyeasy to manufacture and which may be readlly assembled as well asdisassemb ed for purposes of repair or re-' Thus, for example, tlfecarbon electrodes 22 and 31 need not be subjected to special treatmentfor the purpose them. for copper sometimes practice rwhencarbonelectrodes are to be soldered in position instead of conveniently andremovably clam d in position in accordance with the teac is o thedescribed invention. Likewise the rinking of the electrode alloy 33contained within the recess of the member 28 is a very convenient andeffective way to secure material, such as carbon, in a fixed positlon.

readily q The insulating cup 23 which may be 55 which is re- P with amimmum amount of eimolded from suitable insulatin material,

such as phenol condensation-pro note or the as. thefront also ro-v like,'srves as a clamping member as well an insulating, means for separatingand back electrode assemblies an vides a container for the granular caron. Thus it is to be understood that the simplicity of design and thenovel arrangement or: the cooperating parts constituting the describedapparatus, renders possible the manufacture thereof at a minimum costand the product produced has improved transmission characteristics. vAlthough the invention has been described in connection with a certaintype of telehone transmitter, it is to be understood that this inventionis capable of many other a plications and should scope of the appendedclaims.

What is claimed is:

1. In a transmittena resistance varying means including a pair ofelectrodes, a suply of resistance material positioned therebetween, adiaphragm operatively associate one of the electrodes comprisingmetallic materialshaving different coefiicients of e ansion, and asecond diaphragm adapted to actuate one of the electrodes.

2. In a transmitter, a resistance varying means including a pair ofelectrodes, a suply of resistance material positioned there- Ee'tween, abi-metallicdiaphragm operatively associated with one of the electro es,and a second diaphragm adapted to actuate one of the electrodes.

3. In a transmitter, a resistance varying .means including a metallicmember, a carbon electrode removably secured thereto and electricallyconnected therewith, a bi-metallic diaphragm, a carbon electrodeoperatively associated therewith, and an insulating member between thediaphragm and the metallic 4. n a transmitter, .a resistance varyingmeans includin an electrode having a recess, a carbon plate tti withinsaid recess and substantially filling carbon plate and the the carbonplate within the recess. 5. In a transmitter, responsive to pressurevariations, an electrode adapted to be vibrated thereby, a variableresistance means positioned adjacent said electrode, and supp rtingmeans for said e trode comprising a bimetallic member adapted to movethe electrode toward and away from the variable resistance means inresponse to changes in temperature.

6 In a transmitter, a vibratory member respons've to pressurevariations, an electrode adapted to. be vibrated thereby, a variableresistance means positioned, adjacent said electrode, and supportingmeans for said electrode comprising a bimeta 'c diaphragm be limitedonly by t e and a material of low melting point interposed between thewalls of the recess for I 115 a vibratory member adapted to movetheelectrode y, microphonic recessed member and secured therein byadesive material, and means for supporting the recessed membercomprising a bimetallic temperature-responsive 'member having a ortionthereof secured to the recessed memer. y

In witness whereof, we hereunto subscribe our names this 29th day ofSeptember, A. D.

HAL FREDERICK FRUTH. TERRENCE ONAS WESTHAFER.

an electrode

